Shaikat Hossain

The Internet as a Tool for Studying the Collective Unconscious

Abstract This article is a theoretical proposal to use the Internet to explore Jung’s concept of the collective unconscious. Recent findings in the field of sociology have shown that real-life social networks can have strong unconscious effects on the behavior of individuals comprising a group. Such complex interactions have led to the need for a new conception of the collective unconscious, one that incorporates such “group mind” phenomena and is better suited to explore the behavior of large groups of people who are accessible through today’s online networks. This article explores the properties of these networks and establishes a basis for the future exploration of the collective unconscious through such a framework.

Precedence based speech segregation in bilateral cochlear implant users

The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role.

Voice gender and the segregation of competing talkers: Perceptual learning in cochlear implant simulations

Two experiments explored the role of differences in voice gender in the recognition of speech masked by a competing talker in cochlear implant simulations. Experiment 1 confirmed that listeners with normal hearing receive little benefit from differences in voice gender between a target and masker sentence in four- and eight-channel simulations, consistent with previous findings that cochlear implants deliver an impoverished representation of the cues for voice gender. However, gender differences led to small but significant improvements in word recognition with 16 and 32 channels. Experiment 2 assessed the benefits of perceptual training on the use of voice gender cues in an eight-channel simulation. Listeners were assigned to one of four groups: (1) word recognition training with target and masker differing in gender; (2) word recognition training with same-gender target and masker; (3) gender recognition training; or (4) control with no training. Significant improvements in word recognition were observed from pre- to post-test sessions for all three training groups compared to the control group. These improvements were maintained at the late session (one week following the last training session) for all three groups. There was an overall improvement in masked word recognition performance provided by gender mismatch following training, but the amount of benefit did not differ as a function of the type of training. The training effects observed here are consistent with a form of rapid perceptual learning that contributes to the segregation of competing voices but does not specifically enhance the benefits provided by voice gender cues.

Ideal binary masking based noise reduction and interleaved processing for bilateral cochlear implant users

The present study investigates the interaction between ideal binary masking (IdBM) noise reduction and interleaved processing for bilateral cochlear implant (CI) users and normal-hearing (NH) listeners attending to vocoder simulations. IdBM decomposes a signal into time-frequency (T-F) bins and retains only regions where the target is higher than a local threshold (LC). IdBM benefits in CI users have been found to be limited due to factors such as current spread from neighboring electrodes. Interleaving channels across ears in bilateral CI users has been one approach to mitigating the effects of current spread. In the present experiments we tested NH listeners attending to vocoder simulations and CI users with IEEE sentences presented from different azimuths in speech-shaped noise at 5 dB signal-to-noise ratio and IdBM processing with LC values of 5 and -10 dB. Speech intelligibility was poorer for the interleaved condition in the presence of noise. As predicted, however, greater IdBM benefits were found ...

Perception of voice gender in cochlear implant simulations of children's speech

Previous studies [Assmann et al., J. Acoust. Soc. Am. 135, 2424 (2014) and Assmann et al., J. Acoust. Soc. Am. 138, 1811 (2015)] investigated normal-hearing listeners’ ability to discriminate gender and age in children’s speech. The speech stimuli were /hVd/ syllables produced by 140 speakers, ages 5 through 18, and processed using the STRAIGHT vocoder to simulate a change in speaker gender. Experimental conditions involved swapping the fundamental frequency contour (F0) and/or the formant frequencies (FF) to the opposite-sex average within each age group. The present study extended these previous experiments by presenting the stimuli to normal-hearing listeners through a cochlear implant simulation implemented as a sine wave vocoder. Supporting findings reported at previous meetings, swapping F0 has a larger effect on perceived gender than swapping FF for older voices, and single-parameter changes (swapping either F0 or FF), had relatively small effects on older male voices but pronounced effects on olde...

Ideal binary masking and the integration of spectro-temporal glimpses in cochlear implant simulations

Ideal binary masking (IdBM) can improve listeners’ speech recognition scores in the presence of background noise. It retains the time-frequency (T-F) regions where the target dominates the noise while discarding the remaining regions. Li and Loizou (J. Acoust. Soc. Am. 123, 1673-1682, 2008) suggested that IdBM is effective because the pattern of target-dominated T-F units (IdBM pattern) directs the listener’s attention to target glimpses. This study extends the above explanation and investigates listeners’ abilities to integrate target glimpses when the IdBM pattern is held constant. Speech-shaped noise maskers were added to IEEE target sentences at a signal-to-noise ratio of -5 dB and the mixture was processed with IdBM. The IdBM-processed mixture was then decomposed into the IdBM-processed target and masker. The IdBM-processed target/IdBM-processed masker power ratio (TMR) was then varied to produce an altered IdBM-processed mixture. These processed signals were either sent to an eight-channel tone-voco...

A developmental study of vowels spoken in syllables and in sentence context

This study examined the effects of context on the production of vowels spoken by children of different ages in isolation and in a carrier sentence. Vowels were extracted from a database of hVd syllables produced by 208 native English talkers from the North Texas region, ranging in age from 5 to 18 years with approximately equal numbers of males and females. Preliminary analysis of a subset of the database (around 40% of talkers) showed a systematic reduction in vowel duration for syllables in isolation and for those spoken by older children. Vowels in sentence context were approximately 30-40 percent shorter than in isolated syllables, and durations were less closely linked to age group. Formant frequencies (F1 and F2) showed similar patterns for vowels in isolated syllables and sentences, and decreased as a function of age as expected. However, measures of formant movement across the vowel (from 20 to 80 percent of the vowel duration) revealed increased F1 and F2 movement for syllables in isolation compared to those produced in carrier sentences. A comprehensive analysis of the database is presented and implications for vowel recognition will be discussed.

Music masking speech in hybrid cochlear implant simulations

The present study investigated the masking effects of various musical instruments on speech processed through simulations of a cochlear implant (CI) and electric-acoustic stimulation (EAS) at different signal-to-noise ratios (SNRs). Musical instruments with spectrotemporal characteristics similar to speech were generally more effective maskers. Introducing low frequency acoustic information led to improved word recognition scores for the EAS simulation compared to the normal CI simulation. Overall, EAS benefit was larger at lower SNRs. Fundamental frequency (F0) was better preserved in the EAS simulation and found to correlate with EAS benefit, consistent with theories that attribute its effectiveness to F0-based segregation.

Benefits of voice gender and perceptual learning on the perception of masked speech processed through cochlear implant simulations.

Cochlear implant simulations were used to investigate the potential benefits of auditory perceptual training for cochlear implant users. Listeners with normal hearing attended to speech masked by a competing talker, processed through a simulation of an eight‐channel cochlear implant. The aim was to determine whether perceptual training would enable listeners to benefit from differences in voice gender between target and masker. Thirty adults with normal hearing were randomly assigned to one of three training groups: matched‐gender word recognition, mismatched‐gender word recognition, or gender recognition. Participants completed 2 h of training within a 1‐week period then returned 1 week later for a late‐post testing session. Training sessions consisted of ten blocks during which the SNR (−6, 0, 6 dB) was adapted based on performance. Significant speech intelligibility improvements were observed from pre‐ to post‐sessions for all three training groups, and these improvements were maintained at the late‐po...